#include <iostream>
#include <vector>
#include <queue>
#include <utility>
using namespace std;

int dx[4] = { 0,0,1,-1 };
int dy[4] = { 1,-1,0,0 };
bool vis[51][51];
int m, n;

int maxAreaOfIsland(vector<vector<int>>& grid) {
    m = grid.size(), n = grid[0].size();
    int ret = 0;

    for (int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
        {
            if (grid[i][j] == 1 && !vis[i][j])
            {
                ret = max(ret, bfs(grid, i, j));
            }
        }
    }
    return ret;
}

int bfs(vector<vector<int>>& grid, int r, int c)
{
    int count = 1;
    queue<pair<int, int>> q;
    q.push({ r, c });
    vis[r][c] = true;

    while (q.size())
    {
        //auto [a, b] = q.front();
        auto p = q.front();
        int a = p.first, b = p.second;
        q.pop();
        for (int i = 0; i < 4; i++)
        {
            int x = a + dx[i], y = b + dy[i];
            if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == 1 && !vis[x][y])
            {
                q.push({ x,y });
                vis[x][y] = true;
                count++;
            }
        }
    }
    return count;
}


int main()
{
    return 0;
}